<template>
  <div>
    <p>请选择你要购买的书籍</p>
    <ul>
      <li v-for="(item, index) in arr" :key="index">
        {{ item.name }}<button @click="addbook(item.price)">买书</button>
      </li>
    </ul>
    <table border="1" width="500" cellspacing="0">
      <tr>
        <th>序号</th>
        <th>书名</th>
        <th>单价</th>
        <th>数量</th>
        <th>合计</th>
      </tr>
      <tr v-for="(item, index) in arr" :key="index">
        <th>{{ index + 1 }}</th>
        <th>{{ item.name }}</th>
        <th>{{ item.price }}</th>
        <th>{{ item.count }}</th>
        <th>{{item.Totalprice}}</th>
      </tr>
    </table>
    <p>总价格为:{{amountTo}}</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      arr: [
        {
          name: '水浒传',
          price: 107,
          count: 0,
          Totalprice:0,
        },
        {
          name: '西游记',
          price: 192,
          count: 0,
          Totalprice:0,
        },
        {
          name: '三国演义',
          price: 219,
          count: 0,
          Totalprice:0,
        },
        {
          name: '红楼梦',
          price: 178,
          count: 0,
          Totalprice:0,
        },
      ],
    }
  },
  //函数 点击增加数量
  methods: {
    addbook(price) {
      this.arr.forEach((item) => {
        if (item.price == price) {
          item.count++
          item.Totalprice = item.price*item.count
        }
      })
    },
  },
  computed:{
    amountTo() {
    return this.arr.reduce((amount, item) => amount+ (item.price*item.count),0)
    }

  }
}
</script>
